1. Field of the Invention
The present invention relates to an image capture device such as a digital still camera or a digital movie camera.
2. Description of the Related Art
A conventional image capture device is disclosed in Japanese Patent Application Laid-Open Publication No. 2007-163561.
The image capture device includes a means for setting a flash-ON sequential shooting mode and a switching means for switching the imager reading methods into a pixel mixing drive when the flash-ON sequential shooting mode is selected. In this manner, in performing sequential shooting with the flash fired, this image capture device compensates for the lack of quantity of light received by the imagers and increases the read rate of the imagers.
Meanwhile, there is also an image capture device that regulates the amplification gain in such a flash-ON sequential shooting mode. In order to compensate for the lack of quantity of light received by the imagers, the amplification gain is added to an amplifier means for amplifying the image signals that have been generated by the imagers.
To keep the sequential shooting speed equal to or higher than a predetermined value when the sequential shooting is carried out with the flash fired, the maximum intensity of the flash light to be fired while the sequential shooting is actually carried out could be defined to be lower than that of the flash light to be fired while the subject is shot only once (which will be referred to herein as “single shooting”).
In that case, however, when the sequential shooting is carried out with the flash fired, the intensity of the flash light to be fired every time the subject is actually shot would decrease so much that the imaging means such as the imagers should have their sensitivity to light increased significantly. That is to say, to compensate for the lack of light of the imaging means, the image capture device should increase the amplification gain of the amplifier means significantly. Such a significant increase in the amplification gain of the amplifier means, however, would cause a steep decrease in the signal to noise ratio (SNR) of the image signal that has been output from the imaging means and then amplified.
On the other hand, the imaging means could also have its sensitivity to light increased significantly in accordance with the user's settings. In that case, the amplification gain of the amplifier means should also be increased too much that the SNR of the image signal that has been output from the imaging means and then amplified would decrease steeply.
Furthermore, even when the image capture device has a mode of automatically setting the shooting conditions, the imaging means could also have its sensitivity to light increased significantly. Then, the amplification gain of the amplifier means should also be increased so significantly that the image signal would have a steeply decreased SNR when output from the imaging means and amplified.
It is therefore an object of the present invention to provide an image capture device that can generate an image signal with reduced noise while taking the resolution into account even when its imager needs to have its sensitivity to light increased.